


The Red Violin

by Rowanwood_Greenslow



Category: Assassination Classroom
Genre: Anal Sex, Aphrodisiac spit, Blowjobs, Bottom Shiota Nagisa, Demon AU, Demon!Karma, I promise, I've lost my mind, Kinky demon sex, M/M, Magical demon tail, PWP, Rimming, Spit as lube...kind of, There is consent, Top Akabane Karma, Violinist!Nagisa, i think, there is some plot
Language: English
Status: Completed
Published: 2020-05-28
Updated: 2020-05-28
Packaged: 2021-03-03 05:13:42
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,658
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24429301
Author URL: https://archiveofourown.org/users/Rowanwood_Greenslow/pseuds/Rowanwood_Greenslow
Summary: After Nagisa's grandfather dies, he inherits his prized violin and his house. Little does he know, someone else lives in the house and has taken a liking to him.ORKarma (kind of) abducts Nagisa to have some kinky demon sex. ;)
Relationships: Akabane Karma/Shiota Nagisa
Comments: 7
Kudos: 347





	The Red Violin

**Author's Note:**

> Not beta'd. Sorry.

“Nagisa, your grandfather, Ken Shiota, passed away last night. We know you were close, and I offer my condolences. The reading of the will is on Monday at five o’clock.” The call cut off, replaced by a faint buzzing on the line, and Nagisa sank onto the couch, the phone falling from his shaking hands as tears rolled silently down his face. His grandfather, a world-famous violinist, had cared for him after Nagisa’s father died in a plane crash while coming home from an overseas business trip. His mother, not wishing to live without her husband, stabbed herself soon after and was discovered by the seven-year-old son she couldn’t bring herself to love. The old violinist had been the one to comfort Nagisa late at night when he woke screaming, bloody kitchen knives and pale skin haunting him whenever he closed his eyes. Only his grandfather assured Nagisa that no matter how much the boys at school bullied him for his small, feminine stature, it didn’t mean that Nagisa was weak. He was the only person that Nagisa had stayed in touch with after graduating high school, his best friend and closest confidante. And now, he… he was gone. Nagisa didn’t want to believe it, he refused to, but he knew, in his heart, that it was true. Ken Shiota was dead.  
___________________

That Monday, at five o’clock, Nagisa dragged himself into the lawyer’s office, his head hung and shoulders slumped.

“Ah, glad to see you, Nagisa,” the lawyer chirped, smiling brightly and twisting green hair around her finger flirtatiously. “Now that you’re here, should we start?” Nagisa nodded imperceptibly and slid weakly into a chair around the table, zoning out as the lawyer began to read from the will. The fluorescent lights of the office started to fade as Nagisa nodded off, and...

“Nagisa!” Nagisa jolted upright, finally lifting his head as he scanned the room. The lawyer gasped, one perfectly manicured hand flying to her mouth in shock. Nagisa’s hair, usually well-kept and tied back, hung limply around his face, greasy and neglected. His face had a ghostly pallor, and dark rings circled his blood-shot eyes. The lawyer shifted uncomfortably in her seat as she composed herself. 

“Nagisa, your grandfather left you his house and everything in it, including his musical scores and his violin, in hopes that you remember him fondly. “

“Thank you,” Nagisa replied hoarsely, speaking for the first time since entering the room as he made to take his leave.

“Nagisa,” the lawyer started as the haggard man opened the office door. “If you need anything, just tell me. And really, I truly am sorry for your loss.” Nagisa looked back at the green-haired woman.

“Thanks, Kayano, but I think I’ll be out of touch for a while.”  
___________

Nagisa gazed reverently at the scarlet-lacquered violin in his hands. Though Ken Shiota had indulged his grandson shamelessly, even teaching him to play the violin, Nagisa had never once been allowed to touch his grandfather’s most prized possession. And now it was his! Nagisa was struck with the inexplicable feeling of loneliness. Carefully, Nagisa lifted the violin from the case and, placing it on his shoulder, he began to play his favorite piece, the one his grandfather would play late at night in the parlor when he thought Nagisa was asleep. Tartini’s Violin Sonata in g minor. The “Devil’s Trill Sonata.”

As his fingers flew seamlessly across the strings, his bow coaxing a mournful lament from the instrument, Nagisa felt at peace for the first time since his grandfather’s death. A few seconds into the tempo guisto, a burden lifted from Nagisa’s shoulders. He smiled, tears running down his face as he played. In the six months after Ken Shiota’s death, Nagisa hadn’t once dared to pick up a violin, and he had forgotten the intoxicating rush of performing. For that’s what he was doing now. Performing for the spirit of his grandfather in the dusty parlor of his old mansion. Nagisa’s grandfather had always said that the house was alive, and now Nagisa was starting to believe him. The mansion felt full, even though Nagisa hadn’t seen anyone else. And Nagisa played on in the empty house.

Every day after, Nagisa would serenade the house and the being that occupied it. When it rained, he would play in the attic, the percussive sounds of the rain accompanying him. On days when the weather was especially nice, performances took place in the gardens, open only to the house and its mysterious inhabitant, for the house was surround by acres of forest. Mozart. Paganini. Bach. Tchaikovsky. Wieniawski. Shostakovich. The music of multitudes of composers resounded throughout the halls of the mansion as the days became shorter and the nights longer. Weeks passed, and then months. Nagisa played for the inhabitant of his grandfather’s house long after the scars on his wrists had faded from red to a silvery white, and after he finished, he would sit on the well-worn couch in the parlor and talk quietly to the other resident of the house, content to talk for hours on end with no reply. After some time, the being grew fond of the blue-haired violinist and the ritual of daily performances.  
____________

One day, after all of the leaves had long since fallen and snow blanketed the ground, the being decided to reveal himself to the violinist.

“Nagisa,” a deep voice whispered sensuously. Startled, Nagisa shot to his feet as a red-haired demon materialized in the middle of the parlor. “Nagisa,” the demon repeated, this time slightly louder. “Don’t be frightened. I won’t hurt you.” The bluenette stared openmouthed at the dashing figure in front of him and the leathery, black wings that sprouted from between his broad shoulders. Nagisa knew that he should be frightened out of his mind, but the shiver that ran through his body was decidedly not fear. For some reason, this golden-eyed demon seemed familiar.

“Nagisa,” the demon crooned for a third time, advancing slowly towards the frozen bluenette. “Will you play for me?” Suddenly, as if the handsome being’s words had cast a spell on him, Nagisa felt the irresistible compulsion to play the violin. Life returned to his limbs, and he nodded silently before picking up the red violin. The red-haired demon sank onto the dusty piano bench as Nagisa began to play.

The music began softly, a sorrowful waltz, but as Nagisa played, the sound of the violin grew louder. As his tone strengthened and his surroundings melted away, Nagisa noticed a second line begin to harmonize with the violin. The demon had begun to play the piano, and the harmony line intertwined with Nagisa’s melody, caressing him lightly before filling the parlor. Even as he smiled, tears fell from Nagisa’s eyes as the emotions saturating the music overwhelmed him. When the final chord faded, the bluenette collapsed, exhausted, onto the well-worn couch. The demon smiled and rose smoothly from the piano bench. 

“Liebesleid,” the crimson-haired demon said quietly, the words rolling seductively off his tongue. “’Love’s Sorrow.’ A fitting piece for one such as yourself.” He sat next to Nagisa, and the violinist jolted as rational thought returned to him.

“Who are you?” he demanded warily, rising and taking refuge behind the table on which the violin case perched.

“That’s a wonderful question,” the demon replied, smirking. “Who do you want me to be?” Nagisa, unamused, glared at the being. The redhead laughed. “If you wish to know so much, I will tell you, but it will cost you something in return.”

“Fine,” the violinist spat, shutting the lid of the violin’s case. “Now tell me: who are you?”

“My name,” the demon said grandly, “is Karma.”

“That’s not what I meant, and you know it,” Nagisa growled, whipping around to glare at the golden-eyed male. “WHAT are you?”

“Well, that’s a much more difficult question,” Karma mused. “The easiest way to explain it, I suppose, would be to say that my brethren and I are the physical manifestations of certain… aspects of the human psyche: greed, fear, sloth, anger, envy.” The demon stared pointedly at Nagisa. “Lust. In other words, we are what you humans call ‘demons.’”

If Nagisa was at all surprised, it didn’t show. He stood, poker-faced, and looked the demon up and down critically before sighing.

“I wish you were lying, yet I find myself forced to conclude that you are being truthful based solely on the,” Nagisa coughed lightly,” appendages on your back. They don’t seem to be fake.” Karma appeared pleased when Nagisa mentioned his wings, extending them and preening. 

“Do you like them?” he asked, stretching them slightly to catch the light. “A demon’s wings are one of their most prized assets, second only to our horns.” Karma reached up to stroke one of the gleaming golden horns protruding from his crimson locks. Nagisa looked confused, so Karma decided to elaborate. “Our horns grow in relation to how powerful our magic is, but our wings are used to attract mates.

“Attract mates?” the bluenette asked, more befuddled than before. “Like birds of paradise?” Karma smirked attractively.

“Not quite. Wings display the… assets… of the demon in question.”

“Assets? What do you mean by that?” Nagisa queried, completely bewildered.

“Oh, by the burning pits of hell, are you really that clueless?” Karma exclaimed incredulously, startling the violinist. “I might as well just spell it out for you.” He stood directly in front of Nagisa, towering over the smaller male and murmuring directly into his ear. “My wingspan is directly proportional to the length of my cock, and the distance between my wings is proportional to its diameter. The dark color of my wings signifies my virility, and their luster shows how much I ejaculate. The number and size of the peaks on my wings shows the number and size of the ridges lining said cock, and I haven’t even gotten started on the signifiers of the potency of the aphrodisiac in my saliva, my ability to mind-link and share pleasure, my aptitude for bodily transformations, or any of my other sensation-enhancing abilities.

“Oh,” Nagisa breathed weakly, staring wide-eyed at Karma’s impressive wingspan. “Is that so…” Karma’s golden eyes glinted, and he smirked sadistically. 

“If you don’t believe me, I could always show you the proof,” he drawled, stalking across the hardwood floor, but he received no reply. Nagisa swallowed thickly, his heart in his throat, as the crimson-haired demon advanced, and he thought to himself,

“Maybe being shown proof wouldn’t be all that unpleasant.”

Karma’s smirk grew wider.

“Not at all, Nagisa-kun. Not unpleasant at all.” Nagisa’s eyes grew wide.

“How?” he asked breathlessly, staring at the demon.

“I’m a demon, Nagsia-kun,” he replied smugly. “That should explain everything. Now, back to proving my earlier claims and collecting my payment.”

Karma snapped his fingers, and Nagisa was suddenly transported to what appeared to be a lavishly decorated cave. Obsidian walls glistened in the dim candlelight from the candelabras as Karma, popping into existence behind Nagisa, effortlessly picked him up and lowered him gently onto the black silk sheets covering a giant circular bed in the center of the room. Nagisa’s heart began to race as the golden-eyed demon began to slowly, sensually rid the violinist of his clothes. Tenderly, he lavished Nagisa’s exposed collarbone with kisses as he unbuttoned his white shirt, sliding the garment off of Nagisa’s shoulders to allow for further exploration of the bluenette’s slim figure. As Karma’s claw-tipped fingers pinched Nagisa’s pink nipples, he moaned lustily. 

“Look,” Karma cooed in Nagisa’s ear. “Your nipples are so sensitive. They’ve gotten this hard with only a little teasing.’ The demon smirked. “Nagisa-kun, have you been playing with yourself?” Nagisa whimpered and squirmed under Karma’s penetrating gaze. “You have, you naughty boy!” Karma laughed maniacally as Nagisa looked at him beseechingly. “Don’t worry, Nagisa-kun. It’s arousing.”

The demon suddenly swooped down and enveloped one of Nagisa’s perky buds in his mouth, sucking it hungrily. Nagisa mewled loudly as Karma sensually caressed his naked body, arching his back and grinding his growing erection against the demon’s muscular thigh like a cat in heat. As Karma tormented Nagisa’s tender buds, he snuck a hand around the violinist’s thin waist to pull him flush against his chest before grasping the bluenette’s weeping cock. Nagisa gasped loudly, his shout echoing loudly in the cave, and he clenched his hands, crumpling the silken sheets beneath them. 

“Hng!” Nagisa exclaimed as Karma stroked him firmly, the demon’s mouth abandoning Nagisa’s tenderized nubs in favor of latching onto the base of his neck. Nagisa squirmed in Karma’s lap as he tried to simultaneously thrust up into Karma’s hand and capture the demon’s mouth with his own. Bemused, Karma conceded and let Nagisa draw him into a heated kiss. The demon groaned as Nagisa nibbled on his lower lip and fisted his crimson hair. Realizing that he was quickly losing his self-restraint, Karma broke the kiss, and as Nagisa gasped for air, Karma pushed the violinist onto his back. Nagisa made a small noise of displeasure at the sudden movement.

“Shh,” Karma soothed the agitated man, “I’ll take care of you, don’t worry.” In one swift motion, Karma devoured the entire length of Nagisa’s straining erection. 

“Oooh!” Nagisa exclaimed lustily and began to shallowly thrust up into the demon’s mouth. Karma stared sultrily up at Nagisa as he hollowed his cheeks and sucked hungrily, his golden eyes gleaming behind long, dark lashes. 

“God. Oh god, PLEASE!” Nagisa screamed hysterically as Karma edged him closer to orgasm. “God, please let me cum!” Karma smirked.

“You’re praying to the wrong person. No one can help you here,” Karma growled, running his teeth lightly along the underside of Nagisa’s cock. Nagisa’s mouth opened in a silent scream as his climax rushed through his slight frame at Karma’s words. Karma let Nagisa’s softening prick fall from his mouth as the bluenette breathed raggedly. The lustful demon suddenly flipped Nagisa onto his stomach, splaying the violinist’s lithe body on the black sheets. 

“Ah, Nagisa-kun,” Karma breathed onto the slender man’s neck. “You look so pretty all laid out for me, like a virgin sacrifice for my enjoyment.” Nagisa shuddered with pleasure, and Karma’s golden eyes gleamed as he nudged the violinist’s legs apart to expose his most private place. A small gasp escaped Nagisa’s mouth as he felt a hot, wet muscle prod his tiny, pink hole. 

“No, don’t!” He protested, attempting to crawl away, but Karma’s strong grip on his waist kept him at the mercy of the demon’s wicked tongue. “It’s dirty!” Nagisa tried to push Karma away, but Karma’s sinuous tail pinned his hands above his head.

“Bad boy!” Karma hissed. “This,” he jabbed his tongue at Nagisa’s hole for emphasis, “belongs to me now. You belong to me. Do not think of trying to deprive me of what’s mine.” Karma plunged his tongue roughly into Nagisa’s channel, and Nagisa mewled piteously, his quiet cries spurring the demon on. Karma snaked his tongue deeper into the helpless violinist, eliciting soft moans from the bluenette beneath him. When Nagisa began to thrust his hips backwards, the demon slipped a finger in alongside his tongue, but Nagisa was too engulfed by pleasure to notice immediately.

“Gaaah!” Nagisa exclaimed as the smirking demon’s finger brushed against a tightly packed bundle of nerves in his channel, sending shivers of pleasure throughout the bluenette’s body. “What...,” he gasped breathlessly. “What was that?” Golden eyes met Nagisa’s as the demon raised his head.

“That, my delicious Nagisa-kun, was your prostate.” Karma smirked craftily. “I believe that now is the time to prove my earlier claims, wouldn’t you agree?” Nagisa could say nothing, his head nodding vigorously in agreement. Karma again thrust his tongue into Nagisa, but this time, his tongue morphed into something resembling that of a snake. Using his newly pronged tongue to stretch Nagisa’s hole wide open, Karma forced copious amounts of his viscous saliva into the violinist’s tight channel, ceasing only when the thick liquid began to leak from Nagisa’s clenching pucker. Nagisa stared curiously at the demon.

“Why would you do something so weird?” he asked, but the blue-haired violinist was quickly distracted by a strange sensation in his anus. At first a mild discomfort, the sensation soon became an unbearable burn.

“It hurts!” Nagisa cried. “Take it out! Take it out!” He looked at Karma pleadingly, his eyes watering with unshed tears, and the demon felt a strange twinge in his chest. 

“Shhh,” Karma crooned, stroking Nagisa’s blue hair comfortingly as the small violinist whimpered softly. “The pain will fade soon.” Karma pulled Nagisa against his chest, who nuzzled his head into the crook of Karma’s neck. Seeking to soothe the violinist, Karma caressed the boy’s silken locks and fair skin. Nagisa wrapped his thin arms around the demon’s waist and hugged him tightly, drawing comfort from the warm body curled around his own.

However, their calming embrace did not last for long. The burning sensation in Nagisa’s hole abated, and the violinist’s pained whimpers gave way to lewd moans as he began to rub himself against Karma with flushed cheeks and heavy breath. An uncomfortable but increasingly familiar tightness in Karma’s pants caused him to summon what little concentration he had left and magically undress himself.

“Please, Karma.” Nagisa stared beseechingly at Karma, blue eyes locking on gold, and any remaining self-restraint fell to the demon’s lust-ridden instincts. 

The violinist mewled with pleasure as Karma ran his claws lightly over the pale curve of his ass, the sensation amplified by the aphrodisiac coursing through Nagisa’s veins. Karma untangled himself from Nagisa and reclined against the pillows, revealing his monstrous cock. Nagisa gulped. Ha doubted that it would fit. But the worry quickly flew from his mind when Karma guided Nagisa’s mouth to his straining erection with gentle strength. Timidly, Nagisa stuck out his tongue to catch a pearly droplet of precome sliding down the ridges of Karma’s cock. The musky, bitter taste wasn’t unpleasant, Nagisa found, and he hesitantly took the bulging head of Karma’s erection into his mouth. 

“Fuck, Nagisa. Your lips look so perfect stretched around my cock,” Karma groaned as Nagisa struggled to take the demon deeper. He pumped his hips lightly, and Nagisa gagged when Karma’s cock hit the back of his throat. Karma growled, his eyes narrowing, and his thrusts became more forceful. Even as his eyes shed with unshed tears, Nagisa rutted frantically against the sheets, and he barely registered the strange sensation assaulting his hole. However, notice Nagisa did when the unknown object penetrating him from behind forced muffled moans from his mouth. Karma’s thrusts grew erratic, and he stilled as he shot his load into Nagisa’s eager mouth. Nagisa licked his lips after Karma’s cock left his mouth and preened, filled with gratuitous satisfaction. Karma smirked, some conscious thought returning after Nagisa took the edge off of his arousal.

“Nagisa-kun, did you just come untouched?” Nagisa blinked in confusion and glanced at the bed. Streaks of come decorated the sheets beneath him. “Hell, you’re fucking perfect.”

The object in his ass had stilled when Karma came, but it resumed its wriggling with a vengeance. Nagisa turned to look at the object and whimpered. Something at the end of Karma’s sinuous tail tugged at the rim of his hole as it retreated, and he saw a large, blunt dick exit his hole. Nagisa turned back to Karma, his hole clenching around an object that was no longer there.

“Did your tail just grow a dildo? How?” Karma’s insufferably charming smirk returned.

“I’m a demon, Nagisa-kun.”

“Right,” Nagisa said weakly, choosing to ignore that interesting aspect of demon anatomy for the time being. Karma leaned in to nibble on Nagisa’s ear.

“Besides, you’re all stretched and ready for me.” Nagisa moaned lustily as his cock twitched. Why was this demon so damn hot?

Karma’s monstrous cock already stood at full mast, and it was larger than before, if that was possible. In a daze, Nagisa lifted himself up and sank down on Karma’s erection, gasping. Impatient, Karma grasped the violinist’s waist and pulled him down until his balls were flush with Nagisa’s ass. Nagisa moaned.

“’T’s so deep. Feels good,” he slurred, bouncing on Karma’s cock. The demon pushed Nagisa down and began to thrust forcefully into his tight heat. Nagisa howled with pleasure as he clenched around Karma, coming once again. When Karma pulled out, Nagisa whined at the loss, but he soon found himself on his stomach, Karma penetrating his tender hole. The demon brutalized Nagisa’s prostate, drawing orgasm after orgasm from the violinist until he sobbed. Finally, Karma could hold back no more. His hips stuttered at he fully seated himself in Nagisa and came, filling him with his seed. Spent, he collapsed next to Nagisa and curled around the worn-out boy protectively. 

Nagisa sighed contentedly as he snuggled up to the demon, burying his face in Karma’s chest. 

“Sweet dreams, my lovely virtuoso,” Karma murmured adoringly as the two exhausted lovers drifted to sleep.  
____________

“Good morning, Nagisa-kun,” Karma purred when Nagisa awoke. “You were wonderful last night.” Nagisa flushed, and Karma chuckled. “I’ve brought your violin here, and anything else you desire, I can provide. Stay with me,” Karma beseeched the boy. Nagisa looked into the demon’s affectionate, golden gaze, and any excuse to leave vanished.

“I’ll stay with you… forever,” he promised. Karma’s face lit up, and he smirked, fangs glinting at the corners of his mouth.

“In that case,” he said huskily, “it’s time for round two.” Karma pounced on Nagisa, and the violinists face screwed up adorably.

“Like hell it’s time for round two!” he screeched. “My ass still hurts. No sex for a week.”

Karma’s eyes glinted and he smirked mischievously. It was time to see how long Nagisa could hold on to his resolve.

**Author's Note:**

> Please leave a comment or kudos! I thrive off of feedback!


End file.
